The present invention relates generally to forward flow disc drive storage systems and more particularly, but not by limitation, to a head gimbal assembly for use in a forward flow disc drive that includes an air deflector that operates to reduce windage induced off-track motion.
Disc drives are used as primary data storage devices in modern computer systems and networks. Disc drives use one or more rigid magnetic discs for storage of digital information in a plurality of circular, concentric data tracks, which are defined by servo information written to the disc surfaces. The discs are mounted on a spindle motor which rotates the discs. Transducing heads carried by sliders of head gimbal assemblies (HGA""s) are used to read data from, and write data to, the surfaces of the discs.
The HGA""s each include a load beam, a gimbal and the slider. The load beam includes a flexible beam portion at a proximal end and a rigid beam section at a distal end, to which the gimbal is attached. The rigid beam section of the load beam transfers a pre-load force from the flexible beam portion to the slider which directs the slider toward the disc surface. The slider is joined to the rigid beam section by the gimbal. During operation, the discs rotate at high speed, which generates an airflow that is generally parallel to and in the direction of rotation of the discs. In forward flow disc drives, the generated airflow travels from the proximal end of the load beam toward the distal end where the slider and gimbal are located. Each slider is configured with aerodynamic features that ride on an air bearing established by the airflow. The height at which the slider rides the air bearing is limited by the pre-load force generated by the load beam. The gimbal allows the slider to pitch and roll in response to variations in the air bearing.
Disc drives utilize servo systems to control the position of the transducing head relative to a desired data track using the servo information recorded to the disc surface. As the transducing head travels over a disc surface, it reads the servo information and produces an output signal that indicates its position relative to the tracks. The output signal is demodulated and compared with a reference position signal, relating to a desired track position, to produce a position error signal (PES). The PES is provided to a servo controller that outputs a control signal to an actuator mechanism. The actuator mechanism is connected to the HGA""s by track accessing arms and moves the transducing heads toward the desired position or data track in response to the control signal.
There is a continuing trend in the disc drive industry to provide successive generations of disc drives with ever increasing data storage capacity and data transfer rates. Because the amount of disc surface available for the recording of data remains substantially constant (or even decreases as disc drive form factors become smaller), substantial advancements in areal recording densities, both in terms of the number of bits that can be recorded on each track as well as the number of tracks on each disc (measured as tracks per inch or TPI), are continually being made in order to facilitate such increases in data storage capacity. Additionally, efforts are being made to increase data access speeds and provide higher data transfer rates in disc drives.
One way of achieving faster data access and transfer rates is by increasing the rotational speed of the discs. Unfortunately, as the rotational velocity of the discs is increased, the airflows in the disc drive increase in velocity and become more turbulent. Such turbulent airflows, or windage, randomly impact the slider causing the supported transducing head to deviate from the desired track-following path. This off-track movement of the transducer interrupts disc drive read and write operations and produces random non-repeatable runout (NRRO) off-track error in the PES, which cannot be compensated for. As a result, disc drive read and write operations can be temporarily interrupted when the transducing head is moved off-track due to the high energy windage impacting the slider.
Such interruptions of disc drive operations can be reduced by including a microactuator in the HGA controlled by a high performance servo controller. These components provide quick adjustment to the position of the slider/transducer in response to windage induce movement and reduce the duration of interruptions to the read and write operations. However, in addition to making the disc drive more expensive, the constant monitoring and repositioning of the transducing head using the microactuator and servo controller require a great deal of energy over time, which reduces the operational runtime of battery powered systems.
Further advancements in disc drive design are required to improve current disc drive performance by reducing windage induced off-track motion of the transducing heads. Embodiments of the present invention provide solutions to this and other problems, and offer other advantages over the prior art.
The present invention is directed to a head gimbal assembly (HGA) for use in a forward flow disc drive that operates to reduce windage induced off-track motion of a supported transducing head. The HGA generally includes a load beam having a longitudinal axis and a disc side, a gimbal, a slider, and an air deflector. The gimbal is mounted to a distal end of the load beam. The slider includes a transducing head and is mounted to a disc side of the gimbal and is aligned with the longitudinal axis of the load beam. The air deflector includes a first deflecting member that is positioned upstream of the slider relative to a forward airflow. The air deflector extends from the disc side of either the distal end of the load beam or the gimbal, and across the longitudinal axis. The air deflector deflects a portion of the forward airflow away from the slider to thereby reduce windage induced off-track motion of the transducing head.
Other features and benefits that characterize embodiments of the present invention will be apparent upon reading the following detailed description and review of the associated drawings.